BAGHDAD, Feb. 9 -- On Nov. 3, U.S. soldiers raided a safe house of the insurgent group al-Qaeda in Iraq near the northern city of Balad. Not a single combatant was captured, but inside the house they found something valuable: a diary and will written in neat Arabic script.

"I am Abu Tariq, Emir of al-Layin and al-Mashadah Sector," it began.

Over 16 pages, the al-Qaeda in Iraq leader detailed the organization's demise in his sector. He once had 600 men, but now his force was down to 20 or fewer, he wrote. They had lost weapons and allies. Abu Tariq focused his anger in particular on the Sunni fighters and tribesmen who have turned against al-Qaeda in Iraq and joined the U.S.-backed Sunni Sahwa, or "Awakening," forces.

"We were mistreated, cheated and betrayed by some of our brothers," Abu Tariq wrote. "We must not have mercy on those traitors until they come back to the right side or get eliminated completely in order to achieve victory at the end."

The diary is the U.S. military's latest weapon in a concerted information campaign to undermine al-Qaeda in Iraq and its efforts to regroup and shift tactics. The movement remains strong in northern areas, and many American commanders consider it the country's most immediate security threat. In recent days, U.S. officials have released seized videos showing the Sunni insurgent group training children to kidnap and kill, as well as excerpts of a 49-page letter allegedly written by another al-Qaeda leader that describes the organization as weak and beset by low morale.

"It is important we get our story out," a U.S. military official said on condition of anonymity. "I firmly believe the information part of this conflict is as very vital as the armed element of it. . . . We don't want to lose that to al-Qaeda."

A scanned copy of the diary with names redacted with black ink was provided to The Washington Post on Saturday. Its contents provide a rare glimpse into the thoughts of an embattled al-Qaeda in Iraq leader, as well as a snapshot of an insurgent movement that is in turmoil in some parts of Iraq. It also reflects a growing conflict among Sunnis. Since October, attacks by al-Qaeda in Iraq against the Awakening fighters have doubled, said Maj. Winfield S. Danielson III, a U.S. military spokesman.

U.S. military officials said they are convinced the diary is authentic. Most, if not all of it, was written in October, and its tone of anger and bitterness is consistent with security improvements they were seeing in Balad at the time, they said. An estimated 450 Sunni Awakening fighters, also known to the U.S. military as "concerned local citizens," are now providing security in the area. The Post could not independently verify the diary's authenticity.

The U.S. military officials cautioned that the diary was not a portrait of the insurgency across the country. "This is the state of al-Qaeda in this area," the U.S. military official said.

Not much is known about Abu Tariq. U.S. military officials said that they had no one in custody by that name and that it was most likely a pseudonym. Mansour Abed Salem, a tribal leader whose brother leads the Awakening forces in some areas north of Baghdad, described Abu Tariq as the "legal religious emir" of an area stretching from Taji, north of the capital, to south of Balad.

Awakening forces and al-Qaeda in Iraq fighters clashed in that area recently, Salem said. The Awakening forces found 20 decrees signed by Abu Tariq that sentenced to death prisoners his men had captured, including policemen and soldiers. Salem said Abu Tariq had recently fled to Mosul, an al-Qaeda in Iraq stronghold, where U.S. and Iraqi troops are preparing a major offensive.

Throughout the diary, Abu Tariq appears to have been speaking and giving instructions to his followers. He was also keeping a record of sorts, as if anticipating his death.

He provided details of what appears to be one of the ways his group financed its activities -- buying and selling trucks and cars, which he called "spoils." He recorded incomplete transactions, including details of money still owed to his group.

He also described the types of weapons the group had in its arsenal, including 7.62mm machine guns, RPG-9 rocket-propelled grenades and C5 rockets, used to target helicopters and low-flying aircraft.

Here, too, Abu Tariq listed the group members who were holding the weapons. In one entry, he mentioned a comrade who had "2000 C5 rockets and an RPG-9" in his possession but refused to hand them over.

"We do not know what is his intention in that regard," Abu Tariq wrote.

In another entry, Abu Tariq listed the names of some tribesmen who had remained loyal to al-Qaeda in Iraq, noting that "there are very few tribe members who stood by us." He boasted that 16 of his fighters had raided the houses of Awakening fighters, "killing and injuring a lot of them" and burning some of their vehicles, "which affected their morale and resources tremendously."

Abu Tariq devoted much of the diary to a list of remaining al-Qaeda in Iraq members in his sector and those who had betrayed his group, naming individuals, families and tribes. "My request to you is not to be negligent with the deserters/traitors at all," he wrote in an Oct. 28 entry, apparently addressing his followers.

He noted that early on, the group had sought to recruit government employees "to have access, sources and supporters among them in order to gain more information" about the tactics and movements of the Iraqi security forces and the U.S. military, which he describes collectively as "infidels." But his followers should have "no mercy" on their former allies now, he said.

He also provided detailed information about five battalions of fighters, all weakened by desertions or dismantled.

About air defense operations, he wrote that there was one person left who was "willing to work with us to the end" and who had in his possession "three operative batteries (one inoperative) plus five C5 launchers and one 23mm gun."

Abu Tariq's diary ended with a list of people still working for him. There were 38, although he had written two weeks earlier that he had "20 or less" fighters left.

Some of those on the list had remarks next to their names, such as "We have not seen him for more than 20 days so far" or "Left three days ago."

"And that is the number of fighters left in my sector," Abu Tariq wrote.

Special correspondent Muhanned Saif Aldin in Tikrit contributed to this report.